Method of and apparatus for preparing mold surfaces



M. F. HILL METHOD OF AND APPARATUS FOR PREPARING MO LD SURFACES Filed March 18 1920 INVENTOR MY/w/vFH/LL.

KTRSRNEYs Patented Aug. 26, 1924.

MYBON F. HILL, OF NEW YORK, N. Y.

METHOD OF AND APPARATUS FOR PREPARING MOLD SURFACES.

Application filed March 18, 1920.

To all whom it may concern:

Be it known that I, MYRON F. HILL, a citizen of the United States, resident of New York, county of New York, and State of New York, whose post-office address is L3 est 9th St, New York, N. Y., have invented a new and useful Method of and Apparatus for Preparing Mold Surfaces, of which the following is a specification.

This invention relates to methods for providing mold surfaces and the particular object of my invention is to provide a method for preparing thin flat sand molding sur faces and for repairing such surfaces when damaged particularly for those portions of molds which are inverted before casting, such as copes, etc.

The accompanying drawing illustrates the apparatus adapted for the carrying out my invention.

Fig. 1 is a perspective view of a cope of a mold partly filled with surfacing material; Fig. 2 is a similar view showing the cope filled and in process of being packed or rammed; Fig. 3 is a similar view showing the cutting or striking bar in process of surfacing; Fig. 4 shows the method of the final surfacing; Fig. 5 is a detail of the skeleton showing the provisions for ventilation and for holding the filler when the cope is inverted.

The cope comprises a base 6, preferably bounded by a metal frame composed of side channels 7, and end channels 8, suitably fastened together. The angles 9 are supported upon the base by chaplets 10 and clamped by means of bolts and nuts as shown in Flg. 5. Projecting outwardly from the angles or strips are rods or screws 11, having heads or discs 12, rigidly secured to the angles, by welding, if desired. The chaplets 10 are adapted to provide air pockets 10. It is obvious that sand rolled into such a cope construction fails to fill the spaces under the angles, so that gas passageways are left there. The holes through the chaplets and through the base under the chaplets-and elsewhereprovide free escape vents for gases formed during casting.

To fill the cope, I first prepare a mixture of well milled refractory substances, such as sand, silica fiour and fire clay, preferably in the following approximate proportions: silica sand (3) pails; sharp sand (7) pails; silica flour (1) quart; white clay (1 pails. I mix the above mass with a smal Serial No. 366,955.

quantity of water in the usual proportions, preferably containing molasses.

The cope is rammed with the above sand mixture and rolled down by means of a heavy roller 13, whereupon it is leveled by means of a cutting or striking bar 14 with a sharp edge 14. The resulting surface is then covered with riddled sand and rolled smooth; Where the first rolling fails to secure a smooth surface, more of the sand mixture is riddled or sifted on and rerolled. The roller runs on the channels or guideways '7, which prevents the roller from breaking the surface in front of and behind the roller as otherwise would happen. The surface may, if desired, be finally sprinkled over with silica wash or a similar fire proof substance which is non-adhesive to molten metal. iVhen a dry cope is desired, heat is applied preferably until the sand mixture is thoroughly dried.

The cope is now ready to be turned over w1thout the danger of the filler or any part of it dropping out or breaking away.

I find that a cope with a mold surface of the above character produces for thin sheet portions of castings a uniformly level or smooth cast, the surface requiring no sand blasting, as the sand adhering to the casting drops off when rapped sharply. After the cope has been used for making the first casting and removed, the surface of the casting is found to be clean, showing that the filler does not stick to the casting, although, some smaller portion of the filler may have cracked and dropped out. These defects can be readily cured while the cope is still hot, by sprinkling the surface with clay wash, filling the rough places with green sand, and repeating the process and then allowing it to dry from the heat left in the cope from the hot casting just removed.

I found that a cope of the above description will readily retain a filler two inches or more thick, but if necessary the thickness may be reduced, depending upon the number and size of the reinforcing or retaining rods, screws, heads or discs or their equivalent and their distance apart.

The molding surface produced in accordance with the hereinbefore described method clings more tenaciously to the retaining means, that is, to the heads, rods, base, etc. of the cope, than to the casting. Furthermore, the filler is of sufficient porosity to give free vent to the hot gases which are discharged through perforations in the base and the filler is thus relieved of any internal pressure.

Many variations of refractory pulverized or commingled material may be used, provided the substance used is in the main refractory.

The proportions may also be varied with in the limits hereinbefore mentioned.

The process has been shown and described in. connection with the cope of a flask. It is obvious that it may be applied to any other part of the flask, provided the roller and channel or other supports, cooperate to providethe desired sort of surface, flat, curved, or otherwise.

What I claim. is

1. The method of preparing molds which consists of rolling a permeable comminuted refractory filler material onto a multiplicity of rigidly mounted studs or retaining devices to hold the samein place when inverted. I

2. The method claimed in claim 1, and distributing fresh comminuted refractory material over the mold surface with sutlicient binder to cause adhesion and rolling it down flat to the level of a roller guide.

3. An invertible mold construction suitable for retaining molding sand rolled or pressed into the same having a base of large area, and flanges suitable for guides When striking off the sand to provide a thin bed covering said base, and a multiplicity of rigidly mounted studs or sand retaining devices secured directly to said base to hold said thin bed of sand in place when inverted.

4. The combination claimed in claim 3, having secured to said base angles or members carrying said retaining devices and providing said gas passageways between them and said base. v p

The combination claimed inclaiin l, with hollow supports for said members providing gas passageways and acting as rigid supports between said angles or members and said base.

6. The combination claimed in claim 5, having holes thru the base connecting With said gas passageways.

7. The combination claimed in claim 4, having chaplets or their equivalents as rigid supports between said angles or strips and said base.

In testimony whereof, I have afiixed my signature to this specification.

MYRON F. HILL. 

